1. Field of the Invention
The invention relates to imaging.
More particularly it concerns a process for acquisition of one or more radiological image(s) obtained by means of a radiological imaging system, and relates more specifically to those implementing an anti-diffusion grid.
2. Description of Related Art
As shown in FIG. 1, a radiological imaging apparatus includes an X-ray source 10 and an image receptor 11, between which an object of which an image is to be taken is positioned. It is noted that the object can be an anatomical structure, for example a breast in the case of a mammography examination. More generally, it is an object 12 located in a region of interest on a patient.
The source 10 transmits a radiation beam of which the intensity is attenuated as it passes through the object 12, partially by absorption and partially by diffusion in the object. The image receptor 11 is sensitive to the intensity of the radiation.
The presence of the diffused radiation leads to degradation of the contrast of the image obtained and to a reduction in the signal-to-noise ratio, which is particularly disruptive, when details of the object are to be displayed 12.
More specifically, the presence of the diffused radiation leads to degradation of the contrast-to-noise ratio of the image of details of the object.
To overcome this problem, it is known to provide an anti-diffusion grid 13 between the object 12 and the image receptor 11. This grid 13 is positioned in a plane parallel to the plane including the receptor 11, which will hereinafter be called the “grid positioning plane”.
Such a grid is particularly indicated in the case of mammography examinations. In the context of these examinations, a very high detection sensitivity is indeed desired.
FIG. 2 shows a mammography apparatus including an anti-diffusion grid 13.
As known per se, there are cases in which the presence of the grid provides no advantage, i.e. in situations in which the degradation caused by the presence of the grid is no longer compensated for by the advantages procured by its presence, i.e. the rejection of a significant amount of the radiation diffused. This is particularly true when the radiation diffused by the object is significantly lower than the radiation transmitted by the object (in particular when, in mammography, the ratio varies between ¼ and 1).
Such situations are encountered in the following cases: structure with a low thickness and structure placed at a certain distance between the receptor and the source if it is desirable, for example, to image the structure in detail.
Thus, according to the situations encountered, it would be suitable to remove the grid on the basis of the observations and expertise of the operator.
However, this presents the disadvantage of complicating and slowing the examination procedure, since a manual intervention is necessary. Indeed, it is desirable to limit examination times.
Consequently, there is a need to be capable of simply and automatically controlling the use or non-use of an anti-diffusion grid during a radiological examination.